Lecture 21: Muscle EnergeticsSlide Number 2Muscle EnergeticsWhere does the ATP come from?Slide Number 5Slide Number 6Creatine Phosphate PoolSlide Number 8Slide Number 9Slide Number 10SI Integration Session Next Tuesday! Energy Metabolism in the Cell: anaerobic (glycolysis only) & aerobic (glycolysis + oxidative phosphorylation). Clicker questionsAt rest, creatine phosphate levels areThe fastest method of ATP resynthesis in skeletal muscle isWhich method of ATP resynthesis is predominantly used to produce ATP in skeletal muscle at rest?Contribution of ‘energy systems’ to ATP re-synthesisSlide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Suggested Learning ActivitiesLecture 21: Muscle Energetics Office hours: Tuesday and Thursday 1-2pm in Gittings 108 or by appointment Extra office hours posted on D2L Claudia Stanescu, Ph.D.1. Describe the several substrate and/or metabolic sources of ATP used to support muscle contraction and the approximate length of time each is capable of sustaining contraction Objectives: pp. 309-311, sec. 10.4 2. Compare and contrast the characteristics of glycolytic (anaerobic) and mitochondrial (aerobic; oxidative) energy metabolism 3. Define fatigue and describe its most common physiological cause 4. Discuss the Cori cycle and basis of the O2 debtThe immediate source of energy to support development of tension: ATP 1. Hydrolysis by the myosin head group fuels tension generation 2. Hydrolysis by the Ca-pump of the SR supports relaxation Muscle Energetics1) Cell pool of ATP 2) Creatine Phosphate 3) Anaerobic Glycolysis (glucose breakdown) 4) Aerobic metabolism – glucose (from glycogen) – fatty acids (from lipids) – amino acids (from proteins) Where does the ATP come from?Where does the ATP come from? ATP is not ‘stored’ only enough to support ~2 sec of maximal force 1. Cell ‘pool’ of ATP ATP resynthesisWhere does the ATP come from? 2. Creatine Phosphate (CP) pool CP stores ‘high energy phosphate’ the CP ‘pool’ has enough high energy phosphate to support ~15 sec of maximal contraction CPK CPK creatine phosphokinase (CPK)Creatine Phosphate Pool After a meal, ATP + C  ADP + CP During exercise, ADP + CP  ATP + CCreatine •Creatine is a small amino acid-like molecule that is synthesized in the liver, kidney and pancreas and transported to muscle fibers •In a relaxed muscle fiber creatine is 3-6 times more plentiful than ATPWhere does the ATP come from? 3. Glycogen (used anaerobically - glycolysis) occurs in the cytoplasm occurs rapidly! can support ~2 min of contractionWhere does the ATP come from? 4. Glycogen, fat and protein (used aerobically) occurs in the mitochondria relatively slow... can support ~40 min to several hours of contraction (intensity dependent)SI Integration Session Next Tuesday! Looking for an opportunity to practice applying the information that you have been studying for your exam on Wednesday? Come join your peers at our integration session this upcoming Tuesday, October 27th from 6:00-8:00 pm at Park Student Union (upstairs in the Javelina room). This integration session will be a cumulative, application-based session that includes fun, collaboration with your fellow classmates and engaging group activities! We hope to see you all there!Energy Metabolism in the Cell: anaerobic (glycolysis only) & aerobic (glycolysis + oxidative phosphorylation). Glucose plasma membrane Glucose ATP ATP Pyruvate ADP ADP Pi Pi ATP ATP ATP ATP ATP ATP ATP ATP ATP MITOCHONDRION ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP LactateClicker questions • Clicker channel: 70 • Response Ware session ID: psio201At rest, creatine phosphate levels are A. low B. high A. B.76%24%The fastest method of ATP resynthesis in skeletal muscle is A. Creatine phosphate B. Anaerobic glycolysis C. Aerobic glycolysis D. Anaerobic fatty acid oxidation E. Aerobic fatty acid oxidation A. B. C. D. E.64%2%1%10%24%Which method of ATP resynthesis is predominantly used to produce ATP in skeletal muscle at rest? A. Creatine phosphate B. Anaerobic glycolysis C. Aerobic oxidation of glucose, fatty acids or amino acids A. B. C.69%24%7%Contribution of ‘energy systems’ to ATP re-synthesisProgressive increase in the effort required to maintain a desired force, and a progressive inability to maintain this force in sustained or repetitive contractions. Fatigue: Cost of Peak Activity There are many sources of fatigue Psychological Nervous System MuscleFatigue: Cost of Peak Activity Possible Causes: • Glycogen depletion • Lactic acid buildup from anaerobic glycolysis • Phosphate buildup from creatine phosphate metabolismCori Cycle muscle liver Lactic acid Glucose 1. 2.O2 Debt (a.k.a. Excess Post-exercise Oxygen Consumption) O Consumption2Time‘O2 debt’ cost of ‘resetting’ the system after exerciseUniversity of Colorado http://www.colorado.edu/epob/epob1220lynch/08muscle.html Metabolic Equivalents = METSElevated O2 consumption after exercise 1. Lactic acid conversion back to glycogen in the liver (Cori cycle). 2. Resynthesize creatine phosphate 3. Replace oxygen removed from myoglobin 4. Repair Other reasons…Suggested Learning Activities • Create a table of the three methods by which the cell can resynthesize ATP and compare oxygen use, ATP produced, location of reactions, speed of reactions, substrates used and duration. •Draw a graph representing oxygen debt and explain why it takes time for oxygen consumption to return to